The field of the present invention is AC generators, specifically AC generators in automotive-type applications.
AC generators consisting of a housing supporting an internal stator wound with a stator coil electrically excited by the rotation of a magnetically-polarized rotor within the stator coil are well-known in the art. These devices are widely used in automotive, boating, and aviation applications to charge the batteries providing the ignition power in internal combustion engines. These AC generators, or alternators, are lighter and more reliable than the DC generators they have replaced in these applications.
The performance lifetime of the AC generators of the prior art depends to a large degree on the heat dissipation characteristics of the housing. The heat generated by the electric excitation, if not dissipated, can eventually cause failure of the device by causing the stator coil to burn out. In order to dissipate heat the AC generator of the prior art is provided with a centrifugal fan mounted on the rotor to cool the field coil and stator coil. The necessity of the centrifugal fan, however, requires the use of a relatively large housing for the AC generator. With the increasing complexity of automotive internal combustion engines, coupled with the ever-present demand for smaller, lighter, more fuel efficient vehicles, there exists a need in the art for a decrease in the size of AC generators.